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排序方式： 共有524条查询结果，搜索用时 21 毫秒
1.
水体富营养化会导致纸莎草营养状况的变化及次生代谢产物含量的改变。通过典型样地采样和HPLC分析,研究了亚热带高原季风区（昆明）受生活污水污染的沟渠中3种富营养化程度（超富营养一上游、富营养一中游、中富营养一下游）水质对纸莎草地下部生物量和化学成分的影响。结果表明：自上游至下游随着水体富营养化程度的降低,纸莎草地下部生物量显著下降,纸莎草地下部生物量为1．74~3．18kg·m^-2,与原产地相当甚至略高;不同富营养化水质显著影响纸莎草地下部氮、磷的含量,其中中游、下游氮的含量分别较上游下降了43．5％和38．2％,磷的含量分别下降了16．2％和27．7％;不同富营养化水质使纸莎草地下部化学成分发生了显著变化,从上游到下游1-芝麻脂素（38）的含量显著增加,柳杉醇（40）的含量有增加的趋势,黑麦草内酯（18）含量显著减小,猫眼草黄素（35）和青蒿亭（37）的含量受水质影响不大;在未分离鉴定的化合物中,还有10种化合物的含量随着水体富营养化程度的降低而显著增加,有2种显著减少,水质对其他化合物含量的影响不规律。 相似文献
2.
Fresh applications of phosphorus (P) may cause ‘incidental’ losses of dissolved and particulate P forms in land runoff when rainfall interacts directly with fertilizers and manures which are spread, or excreted, onto the soil surface. Research indicates that when incidental P losses (IPL) occur, they often make the dominant (50–98 %) contribution to measured P loads in surface and sub‐surface runoff from field plots, with increased risk of eutrophication where P‐enriched runoff is routed directly to the watercourse. Rates of P loss are temporally and spatially very variable (< 1 to 25 % of total P applied) depending on the amount of P applied; the P release properties of the materials applied (% P extractable in water), the timing of storm events after application and the amounts of runoff generated. Large P applications left on the surface of wet, frozen, compacted, and intensively underdrained soils in high rainfall areas are particularly vulnerable to IPL. Concentrations of P in runoff are often greatest during the first storm event following P application, but can remain high for several weeks, or even months after application. Catchment scale impacts are more difficult to quantify due to the effects of dilution with runoff from fields without IPL, and the contributions of P from other sources. Approaches to predicting IPL are discussed and need to be improved in order to assess the contribution of IPL to catchment P loads in river basin management planning. Strategies to control IPL should focus on adoption of more sensitive management practices in fields with a high risk of rapid runoff or preferential flow, and are likely to very effective. 相似文献
3.
《Reviews in Aquaculture》2018,10(1):111-122
Aquaculture is the main vector for introduction of non‐native species in Brazil and around the world. Despite the potentially serious and irreversible ecological impacts caused by non‐native species, they continue to be in many cases the preferred option in aquaculture farms, of which the recent plans of aquaculture expansion promoted by the Brazilian Government are an emblematic example. In this study, we present a survey of publicly available information on aquaculture parks to be installed across the Brazilian territory, with emphasis on species status as native or non‐native, and discuss the implications for the conservation of aquatic biodiversity. One hundred and thirty‐nine aquaculture parks (AP s), with a total of 1556 sites covering 941.38 hectares, have been called for bids. Among these, 122 AP s will contain at least one non‐native species, and 68 AP s will be based exclusively on their cultivation. A predictable consequence is the enhancement of propagule pressure in surrounding aquatic ecosystems, increasing the risk of non‐native species establishment or persistence, which will likely intensify the environmental impacts already in course in four major river basins and along the Brazilian coast. These impacts will add up to more direct effects of aquaculture farming – for example elevated input of nutrients and organic matter – and include changes in habitat and water quality, spread of diseases, biotic homogenization, loss of population viability resulting from hybridization and outbreeding depression, and the local extirpation of native species. 相似文献
4.
浮床种植草坪草对富营养化水体的净化作用研究 总被引：2，自引：0，他引：2
采用浮床种植草坪草技术,研究了高羊茅Festuca arundinacea、匍匐翦股颖Agrostis stolonifera 2种草坪草对富营养化水体的净化能力.试验结果表明,2种草坪草对富营养化水体中的氮(N)、磷(P)、化学需氧量(CODcr)等具有明显的净化效果,尤其对总磷(TP)的净化能力最强,能有效改善富营养化水体的水质;2种草坪草之间,匍匐翦股颖对TP的去除效果显著高于高羊茅对TP的去除效果.研究结果显示浮床种植草坪草技术可能是一条有效的修复富营养化水域的新途径. 相似文献
5.
6.
富营养化水体中流速对藻类生长的调控作用研究 总被引：2，自引：0，他引：2
水体富营养化问题由于发展快、危害大、处理难及恢复慢等特点,受到全球高度重视.目前国内外在此方面进行了大量试验研究,介绍了国内外关于流速对藻类生长影响的研究成果,探讨水体流速大小和水华发生快慢之间的关系,并指出目前研究主要集中在横向流速对藻类生长的影响方面,对水动力其他要素研究的较少,建议将纵向断面平均流速、素动强度、水面波动特性和横向流速结合起来研究,以求更加全面准确的阐述水动力条件的改变对水质以及藻类生长速率的影响,为制定水华控制措施提供理论依据. 相似文献
7.
K D A Huchzermeyer S Woodborne G Osthoff A Hugo A C Hoffman H Kaiser J C A Steyl J G Myburgh 《Journal of fish diseases》2017,40(11):1665-1680
This study compares the aetiology of pansteatitis in Lake Loskop, relative to two other impoundments along the Olifants River. Macroscopic and microscopic pathology, age determination and analysis of stomach content, fatty acids and stable isotopes explain the high prevalence of pansteatitis in Oreochromis mossambicus (Peters) and several other species in Lake Loskop. All the dietary indicator comparisons between pansteatitis‐affected and healthy fish fail to support a systemic cause. Pansteatitis in Lake Loskop was linked to size and weight of O. mossambicus, but not to ontogenic age. Fish in Lake Loskop showed abnormally high omega‐3 to omega‐6 fatty acid ratios normally only found in marine fish with no significant difference in degree of assimilation of these fatty acids between pansteatitis‐affected and healthy fish. This explains the vulnerability to, but not the occurrence of, pansteatitis. As a cause for the pansteatitis, these results point towards sporadic vitamin E‐depleting trigger events, known sporadic fish die‐off occurrences that provide surviving fish with a rich source of rancid fats on which to scavenge. The mechanism ties pansteatitis to eutrophication and trophic cascade effects, the intrinsic drivers of the disease and suggests an adaptive management strategy that might be applied by relevant conservation authorities. 相似文献
8.
应用\"污染源控制+水生态修复+水质提升\"综合技术治理北太子湖,为城市富营养化湖泊的治理提供技术体系和示范。北太子湖规划蓝线水面面积52.6 hm~2,湖岸线长5km,平均水深1.8 m,工程前水质整体为劣V类,治理目标是湖水水质达到地表水IV类。2018年3月-2019年2月,通过实施污水管网改造、初期雨水调蓄池修建、生态植草沟构建、污染底泥疏浚、湖体水生态系统构建、旁路人工湿地水体提标等工程措施,COD、TN、TP的去除率分别为58.14%、83.18%、90.91%;2019年6-8月水体COD、TN、TP连续3个月达到地表水IV类标准。建议在水生态修复工程完工后,投加一些生态环保型的水质净化剂,提升水体透明度,促进沉水植物快速生长繁殖以发挥净化水质的功能。 相似文献
9.
探讨梅溪湖底栖动物群落结构及其影响因素,为城市人工湖泊水生态系统修复后的运营维护管理提供理论依据。研究结果表明,梅溪湖底栖动物种类达75种,滨岸带种类数高于敞水区。整个湖区全年优势种为米虾（Caridina sp.）、铜锈环棱螺（Bellamya aeruginosa）、椭圆萝卜螺（Radix swinhoei）、大脐圆扁螺（Hippeutis umbilicalis）、霍甫水丝蚓（Limnodrilus hoffmeisteri）和沼虾（Macrobrachium sp.）。敞水区和滨岸带群落结构存在显著差异,除霍甫水丝蚓外,全年优势种是导致两个区域群落结构差异性的主要分类单元。梅溪湖底栖动物现存量和多样性季节间无显著差异,但敞水区和滨岸带之间差异显著,滨岸带远高于敞水区。表明水生植物群落的构建有利于底栖动物种群的壮大和多样性的提高。CCA结果表明,氨氮（AN）和营养水平（TLI）对敞水区和滨岸带的底栖动物群落结构均有较大影响。CoIA分析结果显示,米虾、大脐圆扁螺、铜锈环棱螺、沼虾、椭圆萝卜螺等物种与环境因子存在较为密切的联系,这些物种可以作为梅溪湖水环境条件变化的指示种。梅溪湖底栖动物群落结构合理可控且多样性维持在较高水平,可以有效保障其生态系统的正常运转。 相似文献
10.